Use of the fungus Beauveria bassiana (Bals.) Vuill (Moniliales :Deuteromycetes) for controlling termites

摘要

Entomopathogenic fungi such as Beauveria bassiana (Bals.) Vuill (Order Moniliales: Deuteromycetes have the potentiality to infect insects, resulting in their mortality. It is a beneficial fungus infecting a wide range of insects of the order Lepidoptera, Coleoptera and Hymenoptera, most of which are agricultural pests. The biocontrol potentiality of this fungus has been exploited, making use of the local isolates collected from either soil or from dead insect hosts prevailing in different geographic areas. Control of termites using entomopathogenic fungi has been documented earlier. Metarhizium anisopliae conidia have been formulated and the product named 'BioBlast' has been used to control termites. The mode of treatment of the pest was in the form of fungal baits or pure cultures of the entomopathogen. Workers of the termite colony were targeted more than the soldierss. Dry conidial sprays or mixing the entomopathogen in the soil at 10~8 conidia g~(-1) of soil can be used to control termites for up to a period of 3 months to 3 years under cool, dry, humid conditions; with 100 percent mortality after 10 days of application in the field and 48 h after application in the laboratory. Most of the work on termites has been done using laboratory bioassays, by disturbing the termites from their natural environment and allowing them to crawl/feed on baits containing the entomopathogen. Direct field trials by treating the colonies in their natural environment are meagre. Evaluation of relative pathogenicity of the fungal isolates by classical bioassays is beset with problems, in view of the difficulty to rear on artificial diet and through movement of the termites after application of the inoculum deep into the soil and into the surrounding areas. Collection of data on mortality from different mounds also become unrealistic in view of inadequacy of information on the pest load before treatment, due to their confinement to mounds. In the present study, an attempt has been made to overcome these problems by selecting the uplifted mounds of termites so as to cause least disturbance to their natural habitat and at the same time facilitating collection of mortality data after treatment with local isolates of B. bassiana. The ultimate objective of the study is to select a virulent isolate of B. bassiana for deployment in the development of eco-friendly bioinsecticide for termite control.